EFFECTS OF RESTRICTING LEVOTHYROXINE DOSAGE STRENGTH AVAILABILITY

We conducted a prospective, randomized, controlled trial to assess whe ther hospital formulary restrictions involving limiting dosage strengt hs of levothyroxine affect physicians' ability to manage patients effe ctively and provide pharmacy cost savings in a tertiary care federal g overnment research hospital. Thirty-three endocrinologists were random ly assigned to prescribe levothyroxine from a restrictive (dosage stre ngths of 25, 50, 100, 125, and 150 mu g) or a nonrestrictive (dosage s trengths of 25, 50, 75, 100, 112, 125, 150, 175, 200, and 300 mu g) fo rmulary through a central computer system. Their 241 respective outpat ients' laboratory results and drug compliance were outcome measures. A chievement of treatment objectives was measured by thyroid function te sts (free and total thyroxine, total triiodothyronine, thyrotropin), n umber of clinic visits, and compliance (survey method). Additional mea sures were drug distribution patterns, drug costs, and pharmacy invent ory costs. Restriction of levothyroxine's dosage strength did not sign ificantly alter therapeutic outcomes. However, the restricted formular y was associated with more complex dosing regimens, and resulted in no significant cost savings. It is not known whether such restriction wo uld adversely affect the care of patients of nonspecialists. Prospecti ve studies are required to verify presumed cost-containment measures b efore such measures are adopted for widespread application.